Towards the Adsorption of Propylene and Propane on Cu(I)X and Cu(I)Y Zeolites: Effects of Zeolite Preparation

Abstract

Effects of three different reduction environments on the preparation of Cu(I)X and Cu(I)Y zeolites and their adsorption selectivity towards propylene were investigated. Cu(I)X and Cu(I)Y zeolites were prepared by ion exchange of NaX and NaY zeolites with ammoniacal copper solution, which were reduced in ammonia (1 h and 2 h) or hydrogen flow. Results from inductively couple plasma indicated that there was an incomplete exchange between Cu+ and Na+, which may be from the limitation of this preparation method. The x-ray photoelectron spectroscopy results showed that all reduction methods provided the zeolite with both Cu+ and Cu2+. The breakthrough study was used to investigate the propylene adsorption on the prepared zeolites. Although the results showed that the zeolites selectively adsorbed propylene, which was contributed by the π-complex formation between Cu+ and propylene, it was postulated, in this work, that a certain exchange degree in the zeolites may be required for the effects of the π-complexation to show any noticeable preferential adsorption towards propylene. A decrease in the adsorption capacity of the regenerated zeolites was observed. Cu+ on the Cu(I)Y zeolite was less stable and more susceptible than that on the Cu(I)X zeolite.